The present invention relates to a new and improved construction of measuring apparatus for a multi-part injection mold for measuring the degree of filling of the hollow mold compartment with plastic material injected therein or the closing or closure pressure of the mold and comprises a distance measuring transmitter coupled at one mold part and responsive to changes in the mold gap formed between said one mold part and another mold part.
It has already been proposed to the art in the case of injection molding machines for the processing of plastic or synthetic materials which can be plasticized to correlate the automatic regulation of different magnitudes influencing the degree of filling of the mold, such as for instance the injection pressure, the post-pressure, the dosing volume of the hardening time, to the circumstance that during the injection process under the action of the molding mass injected at high pressure there occurs between two mold parts a relative movement in the sense of opening the mold and thus there can form a more or less large mold gap.
In order to prevent the formation of a much too large flash or seam at the molded article it should be appreciated that the mold gap at the mold parting or separation plane must be small in size. On the other hand, it has been found that in the case of measuring devices utilizing a contactless distance measuring transmitter, especially working on an inductive basis, and which transmitter responds to changes in the size of the mold gap, both the measuring sensitivity and the measuring range are too small when there should not be exceeded an acceptable dimension or size at the mold gap.